I think there is a strong possibility of malfeasance in the upcoming US election, particularly in respect of electronic vote counting (or not counting, as the case may be). WorldChanging (also here) and For The Record have good coverage of the background, and you can take action and learn more at Black Box Voting and Verified Voting.

One of the simplest actions voters can take is to use a postal ballot. This may not be necessary where you are, and it's certainly not a good long-term solution, but for many US voters it may be a good way to sidestep, and register dissatisfaction with, e-voting in the upcoming election. Overseas Vote 2004 is a good way to obtain the necessary paperwork and check the registration deadlines. Beware of state laws regarding eligibility for postal ballots, though: if your vote can be challenged, it will be challenged if the election is at all close.

While I'm at it, don't forget Project Vote Smart, one of the best political resources online.

Don't screw this up, America.